PAPERS ON BOTANY 143 



control of orchard fungi, and Blair et al. (1916), Winn 

 (1916), HoAvitt and Caesar (1917), and Pickett et al 

 (191S), are among those reporting results 'of various 

 spray treatments in sooty blotch control. 



General Appearance. Sooty blotch, as its name im- 

 plies, is made up of spots or blotches, appearing to the 

 naked eye as smears of soot, at first brown in color, 

 darkening with age. The spots, though somewhat irregu- 

 lar in outline, have a tendency to be circular (Figs. 1, 2). 

 Individual areas may vary in diameter from less than 

 .1 cm. to .8 cm., but in most cases before the larger di- 

 mension is reached, t^vo or more blotches will have 

 coalesced, tending to cover the surface of the fruit. 



On closer examination, sooty blotch exhibits a radiat- 

 ing structure of olive brown mycelial threads which ex- 

 tend to form a common center and branch to form a col- 

 ony, fern-like in appearance. 



In all essential particulars, sooty blotch, as found on 

 stems and twigs of various hosts, is similar in appear- 

 ance to that described on the fruit. 



Economic Importance. Sooty blotch is an orchard 

 trouble of considerable importance, in the sections of this 

 country and Canada where it is commonly found. Other- 

 wise high class fruit, when spotted -u-ith the fungus, is 

 reduced materially in market value because of the dis- 

 figuration. According to Winn (1916), fruit is reduced 

 at least one-half in selling price if sooty blotch or 

 ''cloud" is present, while Quaintance and Scott (1912) 

 state that such blotched fruit is rendered ''practically 

 unsalable ' '. 



Wholesale apple buyers in Champaign, Illinois, inform 

 the writer, that in the contract they make with the 

 orchardist to buy his crop, it is expressly stipulated that 

 no "clouded" fruit shall be packed in either the Xo. 1 or 

 No. 2 grade, but must be barrelled separately, and at a 

 discount in price of from twenty-five to fifty per cent. If 

 the "cloudy" stock has to be discoimted more than fifty 

 per cent, it is handled only on a consignment basis. 



